Pulverizing machine



June 8 1926.

D. T. FISHER PULVERIZING MACHINE Original Filed Sept. 17

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WJTNESSES.- j/ QLMU, Y

Patented June 8, 1926.

UNITED STATES PATENT OFFICE.

D'UDLEY T. FISHER, OE COLUMBUS, OHIO. ASSIGNOB, T0 ALEXANDER MAKAFFEY READ, OF COLUMBUS, OHIO.

PULVERIZING MACHINE.

Application filed September 17, 19.20, Serial No. 410,961.

rEhe presentinvention relates to certain new and useful improvements in pulverizing i'nachines of the class in which each consists of a rotatable barrel wherein the material to be pulverized may be tumbled about with freely `lovable crushing bodies and be pulverized by contact therewith.

1 am aware that mills have heretofore been produced comprising a barrel adapted to revolve about its longitudinal axis which is so disposed to the horizont-al that the included material will tend to t-ravel on the lower side of the barrel from the receiving to the discharging end of the mill, and in which the barrel is divided into a series of grinding compartments by screening partitions whereby the material is so classified that the coarser fragments are retained in the forward compartment while the finer particles are passed progressively through the succeeding compartments towards the delivery end of the mill.

lt is the especial object of this invention to provide improved screening partitions whereby such classification of material will be more efficiently accomplished.

The devices by which I attain this object are fully set forth in the following specification and illustrated in the accompanying drawings of which- `Fig. 1 is a vertical longitudinal section of the preferred embodiment of my invention, taken substantially on the line 1 1 of Figure 2.

Fig. 2 is a transverse view taken along the line IIMII of Fig. 1.

Fig. is a fragmentary sectional view taken along the line III-H1 of Fig. 1,

Like numerals refer to similar parts in the several figures.

As shown in the drawings the numeral 1 indicates a barrel adapted to revolve about its longitudinal axis which is so disposed to the horizontal that material within the barrel will tend to travel on the sides of the barrel from the receiving to the delivery end of the mill as the barrel revolves. To the barrel 1 is attached the bearing rings 2 and 3 which bear upon the rollers t and 5 to support the barrel for rotation. The rollers el and 5 are mounted in suitable journal bearings 6 and 7' which are sup-ported upon the foundations of the mill. To the barrel 1 is attached a ring gear 8 which is engaged Renewed October 19, 1925.

by a pinion 9. The pinion 9 is mounted upon a power shaft from which power is derived torevolve the barrel. The upper end of the barrel 1 is closed by a plate 10 to which is secured a cylindrical extension 11. The eX- tension 11 is journaled in a pillow block 12 supported upon the foundation castings 13. The pillow block 12 is provided with the customary removable cap 141 in which is formed a lubricant receptacle 15. 16 is a ball bearing interposed between the outer end of the Jillow block 12 and the flange 17 of the cylindrical extension 11 to prevent longitudinal movement of the barrel. The cylindrical extension 11 and the plate 10 are pierced by a` central bore through which entends a. cylindrical trough 18 formed at the lower end of a feed hopper 19. Positioned within the cylindrical trough 18 is a screw conveyor 20 to the extended shaft of which is attached a suitable pulley 21 adapted to be connected with any convenient lsource of power to rotate the screw conveyor 20 and thereby transfer material from the feed hopper 19 to the interior of the barrel 1. rl`he lower end of the barrel 1 is closed by a transverse wall 22 provided with screening apertures adapted to permit the escape of the finely pulverized material from the interior of the mill while retaining the over sized material for further grinding. The size, form and arrangement of the screening apertures are subject to wide variation to suit the requirements of material of different characters and the desired lineness of the product. These apertures pref crably expand outwardly to prevent the lodgment therein of fragments of material and the consequent choking of the screen.

As the fineness of grinding is directly related to the duration of time the fragments of material are retained within the mill, I prefer to for n the barrel 1 with such a taper that when mounted upon a horizontal axis, as shown in 1, the rate of flow of the material longitudinally/'of the mill `will carry said material to the discharge ends at the precise moment it is pulverized to the desired degree of ineness.' 'It is appar ent that if the taper of the mill were increasedit might be necessary incline the 4axis of rotation upwardly `to prevent the material flowing too rapidly through the milh and if the sides of the barrel were made less tapering', or parallel, it would be necessary to incline the axis downwardly to pro` duce the desired rate of travel.

The friction of the material againstthe sides of the barrel cause the lower part of its mass to be moved upwardly with the ascending side of the barrel, while the upper portion of the mass slides downwardly, maintaining a continuous orbital movement ofthe fragments of which the mass is composed, and the friction due to this movement is an important element in producing a grinding action of the mill. The grinding balls, being of greater specific gravity than the fragments of material which is being pulverized, gravitate toward the lower part of the mass and become buried beneath the lighter material. These halls are carried upward with the side of the barrel to an elevation depending upon the angle of repose which` is a characteristic of the material under treatment, and to the centrifugal force due to the velocity of rotation. At the point of maximum elevation the material falls away from the side of the barrel and the grinding balls roll upon the surface of the mass, striking fragments of material lying upon the lower side of the barrel to break them by their percussive aetion,thereby materially assisting in pulverizing the material.

Vhen a mass composed of freely movable fragments of various .sizes but of the same specific gravity is agitated, the finer particles tend to slip through the interstices between the larger fragments, and the larger fragments tend to float to the surface, resultingv in a more or less complete stratification of the mass relative to the size of its component fragments. Due to the tendency to stratification. and the inclination of the lower side of the barrel, the finer particles of material sink to the bottom of the mass and travel longitudinally of the mill tending to accumulate against the surface of the screen 22. Owing to the slippage of material against the surface of the mill this accumulation of fine material slides across the screening apertures as the mass is carried upwardly and the smaller fragments are forced through these apertures by the weight of the material upon them. From the point of maximum' elevation the material rolls downwardly across the face of the screen and the small fragments pass through the screening apertures while the larger fragments are retained within the pulverizing chamber. y As the largerv fragmentsof the material which is to be pulverized can only be broken by contact with relatively llarge and heavy grinding bodies, as the most efficient reduction of the finer particles is accomplished by a large number of relatively small grind- .ins bodies, and. as the Size, Qfthe-omp0neat fragments of the material within the mill is progressively reduced from the receiving towards the discharge end, it is apparent that a corresponding classification of the grinding bodies is desirable. To accomplish such classification l have divided the barrel l into a series of grinding compartments A, B, C and D by the transverse screens 23, 24: and 25 which are similar to the screens 22 but are respectively provided with apertures of progressively decreasing dimensions the screens nearest the receiving end having the largest apertures. By this arrangement of screens the material in the successive compartments of the mill is classified relative to the size of its component fragments, and each grinding compartment is provided with grinding bodies of a size appropriate to the most efficient grinding of the material in said compartment.

I am aware that grinding mills have been proposed with transv rse screens dividing the interior of the barrel into a series of pulverizing chambers, but, as heretofore constructed, the pressure of material upon the rearward side of the screen tends to prevent the movement of fragments through the apertures of the screen thereby interrupting the fiow of material through the mill. It is desirable to provide at the rear face of the screening partition of a mill, such as this, some means adapted to engage the material, which tends to haelt up against the face of the screen, and to throw the material forwardly within the barrel away from the partition apertur To overcome this difficulty I have provided at the rearward side of the screens 23, 2st and 25 a plurality of radially extending wings 26 which are inclined to the surface of the screen as shown in Fig. El, and which tend, as the mill revolves, to throw trie material away from the rearward side of the screen in the manner of a plowshare. lt will be noter, that the wings have outer portions which extend over the face of the screens. or are inclined to the screen surface. rl`hus, as the barrel revolves, the wings do not pick up the material, but inferely deflect 'the same. Moreover, there is formed at the concave side of each wing a pocket, as is shown in Figure f3, adapted to receive the material passing through the screening apertures. The inclination of the wings serves to prevent the deected inaicrial from immediately crowding or bal:- ing up against the screen, as would occur if the wings merely projected outwardly from the face of the screen without inclination. By the eddying 1n vement thus caused in the material adjacent the rearward side of the screens 23, 24 and 25, as diagrammatically illustra-ted iny Fig. 3, there is created a' series of voids, a, Z7, and e .intenties ,filamenti-e1, 0f the .Pl'eflllg Leerweg 3 chambers inay :Freely [loiv through the aper tures ot the respective screens, inaterially increasing the e'liiciency of the screen and achieving the desired classification ot' the z(grinding bodies Without interrupting the flow oit i'uaterial through the iiiill.

At the delivery end ot the barrel l I have provided a receiving chamber 2.7 having flanges which torni' a dust tight joint with the sides oi" the barrel l and which is provided with a spout 29 to con* duct thl ii'iaterial 'troni the niill Lo any prei" rred destiiiation.

lfilhat I elaiin isl. In a pnlverizing iiiill ot the class described, the combination vfith an approxiinately horizontal barre adapted to revolve about its longitudinal oi' a transverse partition dividing the interior ot the barrel into grinding ci ainliers, said partition having a plurality of screening` apertures, and iiieans extending` 'r'ioni approxiniately the periphery of the partition inwardly on the rearward face thereot adapted to engage material adjacent said apertures and to deflect it longitudinally oi the iiiill away i'roni the apertures.

2. In pulif'erizing' inill oit the classl described, the combination with an approxiniately horizontal barrel adapted to revolve about its longitudinal axis, ot a transverse partition forming a grinding chainber, said partition having' a plurality of screening;l aj'iertures, and ineans projecting 'troni the rear face ot the partition extending;` across the sane and having` a laterally directed portion spaced from the surface ot the partition, said iiieans being adapted to engage material adjacent said apertures 'and detlect the saine longitudinally ot the iiiill aivay frein said apertures.

3. ln a pulverizing iiiill oit the class desciibcd, the combination With an approxiniately horizontal barrel adapted to revolve about its longitadina axis, ot a transverse partition if'orniiiig ay grinding chamber, said uralitj; of screening projectingand efe partition harina a p apertures, a (i Wing ifroin the rear lace of the partition tending; .fartlly from adii i erv oita ina a lai a v Di i' nor-tion e, J .ll i fi'oin tl e race ot the screen, the ving coing spaced adapted to nage iiateria apertures ano ce fro il. ln a pulver f the class dean approxi- -il to revolve inately horizont:

scribed, the coral l( A about its loi itudiual axis, oi a traiiisverse partition V"auf e ulterior oit the barrel and if'oi'nii e,r griniline chaniber, saifl tl c j a plurality or screeiiiuo' apertures, and a series ot subsstntial,y dially attending Wings on the rear i ace oi said partition hailing portions projecting lateraliy offer the surface oi" the screen and spaced t'roxn sa'd surface.

i3. ln a pulverizinp; niill oi the class described` a rotatable barrel, a transverse partition in said liar el ioii'iniiiii' a Igiinfling;` chamber, said partition haring; a plurality oi' screening' apertura; therein, and a plurality of ra dially extending Wings projectiue i'irorii 'the rear 'face ot said jartition, said rings being; inclined to the tace olf the partition.

ln testiinony whereof, l ture.

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